Do check-execstack test using readelf rather than a build-time C program.

scripts/check-execstack.awk

@@ -0,0 +1,52 @@
+# This awk script expects to get command-line files that are each
+# the output of 'readelf -l' on a single shared object.
+# But the first file should contain just "execstack-no" or "execstack-yes",
+# indicating what the default is in the absence of PT_GNU_STACK.
+# It exits successfully (0) if none indicated executable stack.
+# It fails (1) if any did indicate executable stack.
+# It fails (2) if the input did not take the expected form.
+
+BEGIN { result = sanity = 0; default_exec = -1 }
+
+/^execstack-no$/ { default_exec = 0; next }
+/^execstack-yes$/ { default_exec = 1; next }
+
+function check_one(name) {
+  if (default_exec == -1) {
+    print "*** missing execstack-default file?";
+    result = 2;
+  }
+
+  if (!sanity) {
+    print name ": *** input did not look like readelf -l output";
+    result = 2;
+  } else if (stack_line) {
+    if (stack_line ~ /^.*RW .*$/) {
+      print name ": OK";
+    } else if (stack_line ~ /^.*E.*$/) {
+      print name ": *** executable stack signaled";
+      result = result ? result : 1;
+    }
+  } else if (default_exec) {
+    print name ": *** no PT_GNU_STACK entry";
+    result = result ? result : 1;
+  } else {
+    print name ": no PT_GNU_STACK but default is OK";
+  }
+
+  sanity = 0;
+}
+
+FILENAME != lastfile {
+  if (lastfile)
+    check_one(lastfile);
+  lastfile = FILENAME;
+}
+
+$1 == "Type" && $7 == "Flg" { sanity = 1; stack_line = "" }
+$1 == "GNU_STACK" { stack_line = $0 }
+
+END {
+  check_one(lastfile);
+  exit(result);
+}